The present invention relates to an apparatus for blocking a hole, especially an apparatus for blocking a hole that is a passageway of a mold, such as an injection mold or diecast mold.
Injection molds are often machined from thick plates of metal, such as aluminum or steel. By so machining the injection molds with thick cross sections, the dimensional stability of the mold, and also the dimensional repeatability of the molded components, is maintained to a high degree of accuracy. These molds are typically used at elevated temperatures and elevated internal pressures so as to enhance the flow of molten material into the molding cavity.
The usage of the injection molds at elevated temperatures results in some thermal distortion of the molds due to thermal growth. In order to manage this thermal growth, the injection molds are sometimes cooled. In some injection molds, a cooling liquid flows through various passageways drilled within the molds in areas where it is necessary to reject heat. Sometimes in the drilling of these passageways, a passageway may be overdrilled such that it undesirably connects to other intersecting passageways in its path. In cases such as this, it is necessary to substantially block fluid communication between the two intersecting cooling passageways.
In order to block flow between the two passageways, a sealing plug may be inserted within the crossing passageway and placed at a point where it blocks communication between the two intersected passageways. After the plug is placed in location, it may be necessary to take some action to cause the plug to seal the cavity and stay in position. As an example, one sealing plug includes two generally cylindrical members and a fastener for holding the two members together. An O-ring is placed between the two members. As the fastener is tightened, the two members are drawn together and the O-ring is squeezed outwardly so as to seal the hole. However, it is difficult to precisely locate these plugs within a passageway. Sometimes the only way to position the plug is by incorporating a hexagonal socket on the fastener, and pushing the plug into location with an Allen wrench. If the plug is pushed too deep within the passageway, it is difficult to pull the plug out since the Allen wrench does not positively grasp the socket.
In yet other designs, the plugs have external tapered threads. The passageway to the plug must likewise incorporate tapered threads. Cutting these threads into the mold creates burrs and other chips which must then be flushed from the mold. Further, the machining of threads into the mold increase the expense of the mold.
What is needed is an apparatus that overcomes the difficulties of current designs. The present invention does this in a novel and an obvious way.